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Format of IBM/MS INT 13 Extensions drive parameters

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Offset Size Description

00h

WORD

(call) size of buffer (001Ah for v1.x, 001Eh for v2.x, 42h for v3.0)
(ret) size of returned data

02h

WORD

information flags (see #00274)

04h

DWORD

number of physical cylinders on drive

08h

DWORD

number of physical heads on drive

0Ch

DWORD

number of physical sectors per track

10h

QWORD

total number of sectors on drive

18h

WORD

bytes per sector

--- v2.0+ ---

1Ah

DWORD

configuration parameters (see #00278) FFFFh:FFFFh if not available

--- v3.0 ---

1Eh

WORD

signature BEDDh to indicate presence of Device Path info

20h

BYTE

length of Device Path information, including signature and this byte (24h for v3.0)

21h

3 BYTEs

reserved (0)

24h

4 BYTEs

ASCIZ name of host bus ("ISA" or "PCI")

28h

8 BYTEs

ASCIZ name of interface type
  • "ATA"
  • "ATAPI"
  • "SCSI"
  • "USB"
  • "1394" IEEE 1394 (FireWire)
  • "FIBRE" Fibre Channel

30h

8 BYTEs

Interface Path (see #00275)

38h

8 BYTEs

Device Path (see #00276)

40h

BYTE

reserved (0)

41h

BYTE

checksum of bytes 1Eh-40h (two's complement of sum, which makes the 8-bit sum of bytes 1Eh-41h equal 00h)

Note:

If the size is less than 30 on call, the final DWORD will not be returned by a v2.x implementation; similarly for the Device Path info.

See Also:

#00277,#03196